快速入門:使用 Python SDK 和 Azure Cosmos DB 建置 Cassandra 應用程式Quickstart: Build a Cassandra app with Python SDK and Azure Cosmos DB

本快速入門示範如何使用 Python 與 Azure Cosmos DB Cassandra API,以藉由從 GitHub 複製範例來建置設定檔應用程式。This quickstart shows how to use Python and the Azure Cosmos DB Cassandra API to build a profile app by cloning an example from GitHub. 此快速入門也會示範如何使用 Web 型 Azure 入口網站來建立 Azure Cosmos DB 帳戶。This quickstart also shows you how to use the web-based Azure portal to create an Azure Cosmos DB account.

Azure Cosmos DB 是 Microsoft 的全域分散式多模型資料庫服務。Azure Cosmos DB is Microsoft's globally distributed multi-model database service. 您可以快速建立及查詢文件、資料表、索引鍵/值及圖形資料庫,所有這些都受惠於位於 Azure Cosmos DB 核心的全域散發和水平調整功能。You can quickly create and query document, table, key-value, and graph databases, all of which benefit from the global distribution and horizontal scale capabilities at the core of Azure Cosmos DB.

必要條件Prerequisites

如果您沒有 Azure 訂用帳戶,請在開始前建立免費帳戶If you don't have an Azure subscription, create a free account before you begin.或者,您可以免費試用 Azure Cosmos DB,無須 Azure 訂用帳戶,也無須任何費用和約定付款。如果您沒有 Azure 訂用帳戶,請在開始前建立免費帳戶If you don't have an Azure subscription, create a free account before you begin. Alternatively, you can Try Azure Cosmos DB for free without an Azure subscription, free of charge and commitments.

此外,您需要:In addition, you need:

建立資料庫帳戶Create a database account

您必須先使用 Azure Cosmos DB 建立 Cassandra 帳戶,才可以建立文件資料庫。Before you can create a document database, you need to create a Cassandra account with Azure Cosmos DB.

  1. 在新的瀏覽器視窗中,登入 Azure 入口網站In a new browser window, sign in to the Azure portal.

  2. 選取 [建立資源] > [資料庫] > [Azure Cosmos DB] 。Select Create a resource > Databases > Azure Cosmos DB.

    Azure 入口網站資料庫窗格

  3. 在 [建立 Azure Cosmos DB 帳戶] 頁面中,輸入新的 Azure Cosmos DB 帳戶的設定。In the Create Azure Cosmos DB Account page, enter the settings for the new Azure Cosmos DB account.

    設定Setting Value 說明Description
    訂用帳戶Subscription 您的訂用帳戶Your subscription 選取要用於此 Azure Cosmos DB 帳戶的 Azure 訂用帳戶。Select the Azure subscription that you want to use for this Azure Cosmos DB account.
    資源群組Resource Group 新建Create new

    然後輸入識別碼中所提供的同一個唯一名稱Then enter the same unique name as provided in ID
    選取 [建立新的] 。Select Create new. 然後為您的帳戶輸入新的資源群組名稱。Then enter a new resource-group name for your account. 為求簡化,請使用和識別碼相同的名稱。For simplicity, use the same name as your ID.
    帳戶名稱Account Name 輸入唯一名稱Enter a unique name 輸入唯一名稱來識別您的 Azure Cosmos DB 帳戶。Enter a unique name to identify your Azure Cosmos DB account. 因為 documents.azure.com 會附加到您所提供的識別碼以建立 URI,請使用唯一識別碼。Because documents.azure.com is appended to the ID that you provide to create your URI, use a unique ID.

    識別碼只能使用小寫字母、數字及連字號 (-) 字元。The ID can use only lowercase letters, numbers, and the hyphen (-) character. 長度必須介於 3 到 31 個字元之間。It must be between 3 and 31 characters in length.
    APIAPI CassandraCassandra API 會決定要建立的帳戶類型。The API determines the type of account to create. Azure Cosmos DB 提供五個 API:Core(SQL) (適用於文件資料庫)、Gremlin (適用於圖形資料庫)、MongoDB (適用於文件資料庫)、「Azure 資料表」及 Cassandra。Azure Cosmos DB provides five APIs: Core(SQL) for document databases, Gremlin for graph databases, MongoDB for document databases, Azure Table, and Cassandra. 目前,您必須為每個 API 建立個別個帳戶。Currently, you must create a separate account for each API.

    選取 [Cassandra] ,因為在此快速入門中,您會建立可搭配 Cassandra API 使用的資料表。Select Cassandra because in this quickstart you are creating a table that works with the Cassandra API.

    深入了解 Cassandra APILearn more about the Cassandra API.
    位置Location 選取最接近使用者的區域Select the region closest to your users 選取用來裝載 Azure Cosmos DB 帳戶的地理位置。Select a geographic location to host your Azure Cosmos DB account. 使用最接近使用者的位置,以便他們能以最快速度存取資料。Use the location that's closest to your users to give them the fastest access to the data.

    請選取 [檢閱 + 建立] 。Select Review+Create. 您可以略過 [網路] 和 [標記] 區段。You can skip the Network and Tags section.

    Azure Cosmos DB 的新帳戶頁面

  4. 建立帳戶需要幾分鐘的時間。The account creation takes a few minutes. 等候入口網站顯示頁面「恭喜!已建立您的 Azure Cosmos DB 帳戶」。Wait for the portal to display the page saying Congratulations! Your Azure Cosmos DB account was created.

複製範例應用程式Clone the sample application

現在,我們將從 GitHub 複製 Cassandra API 應用程式、設定連接字串,然後加以執行。Now let's clone a Cassandra API app from GitHub, set the connection string, and run it. 您會看到,以程式設計方式來處理資料有多麼的容易。You see how easy it is to work with data programmatically.

  1. 開啟命令提示字元。Open a command prompt. 建立名為 git-samples 的新資料夾。Create a new folder named git-samples. 接著,關閉命令提示字元。Then, close the command prompt.

    md "C:\git-samples"
    
  2. 開啟 git 終端機視窗 (例如 git bash),並使用 cd 命令變更至要安裝範例應用程式的新資料夾。Open a git terminal window, such as git bash, and use the cd command to change to the new folder to install the sample app.

    cd "C:\git-samples"
    
  3. 執行下列命令來複製範例存放庫。Run the following command to clone the sample repository. 此命令會在您的電腦上建立範例應用程式副本。This command creates a copy of the sample app on your computer.

    git clone https://github.com/Azure-Samples/azure-cosmos-db-cassandra-python-getting-started.git
    

檢閱程式碼Review the code

此為選用步驟。This step is optional. 如果您有興趣了解程式碼如何建立資料庫資源,您可以檢閱下列程式碼片段。If you're interested to learn how the code creates the database resources, you can review the following snippets. 此程式碼片段全都取自 pyquickstart.py 檔案。The snippets are all taken from the pyquickstart.py file. 或者也可以直接跳至更新您的連接字串Otherwise, you can skip ahead to Update your connection string.

  • 使用者名稱與密碼值是使用 Azure 入口網站中的連接字串頁面所設定。The username and password values were set using the connection string page in the Azure portal. path\to\cert 提供 X509 憑證的路徑。The path\to\cert provides a path to an X509 certificate.

      ssl_opts = {
              'ca_certs': 'path\to\cert',
              'ssl_version': ssl.PROTOCOL_TLSv1_2
              }
      auth_provider = PlainTextAuthProvider( username=cfg.config['username'], password=cfg.config['password'])
      cluster = Cluster([cfg.config['contactPoint']], port = cfg.config['port'], auth_provider=auth_provider, ssl_options=ssl_opts)
      session = cluster.connect()
    
    
  • 使用 contactPoint 資訊來初始化 clusterThe cluster is initialized with contactPoint information. contactPoint 是從 Azure 入口網站來加以擷取。The contactPoint is retrieved from the Azure portal.

    cluster = Cluster([cfg.config['contactPoint']], port = cfg.config['port'], auth_provider=auth_provider)
    
  • cluster 會連線至 Azure Cosmos DB Cassandra API。The cluster connects to the Azure Cosmos DB Cassandra API.

    session = cluster.connect()
    
  • 建立新的 keyspace。A new keyspace is created.

    session.execute('CREATE KEYSPACE IF NOT EXISTS uprofile WITH replication = {\'class\': \'NetworkTopologyStrategy\', \'datacenter1\' : \'1\' }')
    
  • 建立新的資料表。A new table is created.

    session.execute('CREATE TABLE IF NOT EXISTS uprofile.user (user_id int PRIMARY KEY, user_name text, user_bcity text)');
    
  • 插入索引鍵/值實體。Key/value entities are inserted.

    insert_data = session.prepare("INSERT INTO  uprofile.user  (user_id, user_name , user_bcity) VALUES (?,?,?)")
    session.execute(insert_data, [1,'Lybkov','Seattle'])
    session.execute(insert_data, [2,'Doniv','Dubai'])
    session.execute(insert_data, [3,'Keviv','Chennai'])
    session.execute(insert_data, [4,'Ehtevs','Pune'])
    session.execute(insert_data, [5,'Dnivog','Belgaum'])
    ....
    
    
  • 用來取得所有索引鍵值的查詢。Query to get all key values.

    rows = session.execute('SELECT * FROM uprofile.user')
    
  • 用來取得索引鍵/值的查詢。Query to get a key-value.

    
    rows = session.execute('SELECT * FROM uprofile.user where user_id=1')
    

更新您的連接字串Update your connection string

現在,返回 Azure 入口網站以取得連接字串資訊,並將它複製到應用程式中。Now go back to the Azure portal to get your connection string information and copy it into the app. 連接字串可讓您的應用程式與託管資料庫進行通訊。The connection string enables your app to communicate with your hosted database.

  1. Azure 入口網站中,選取 [連接字串]。In the Azure portal, select Connection String.

    使用Use the [複製] 按鈕 按鈕 (畫面右方) 來複製最高值 ([連絡點])。button on the right side of the screen to copy the top value, the CONTACT POINT.

    在 Azure 入口網站的 [連接字串] 刀鋒視窗檢視及複製存取使用者名稱、密碼及連絡點

  2. 開啟 config.py 檔案。Open the config.py file.

  3. 從入口網站將 [連絡點] 值貼到 <FILLME> 的行 10。Paste the CONTACT POINT value from the portal over <FILLME> on line 10.

    行 10 現在看起來應該會類似Line 10 should now look similar to

    'contactPoint': 'cosmos-db-quickstarts.cassandra.cosmosdb.azure.com:10350'

  4. 從入口網站複製 [使用者名稱] 值,並將它貼到 <FILLME> 的行 6。Copy the USERNAME value from the portal and paste it over <FILLME> on line 6.

    行 6 現在看起來應該會類似Line 6 should now look similar to

    'username': 'cosmos-db-quickstart',

  5. 從入口網站複製 [密碼] 值,並將它貼到 <FILLME> 的行 8。Copy the PASSWORD value from the portal and paste it over <FILLME> on line 8.

    行 8 現在看起來應該會類似Line 8 should now look similar to

    'password' = '2Ggkr662ifxz2Mg==';`'password' = '2Ggkr662ifxz2Mg==';`

  6. 儲存 config.py 檔案。Save the config.py file.

使用 X509 憑證Use the X509 certificate

  1. https://cacert.omniroot.com/bc2025.crt 下載 Baltimore CyberTrust Root 憑證到本機。Download the Baltimore CyberTrust Root certificate locally from https://cacert.omniroot.com/bc2025.crt. 將檔案重新命名為使用副檔名 .cerRename the file using the file extension .cer.

    憑證有序號 02:00:00:b9 和 SHA1 指紋 d4🇩🇪20:d0:5e:66:fc:53:fe:1a:50:88:2c:78:db:28:52:ca:e4:74The certificate has serial number 02:00:00:b9 and SHA1 fingerprint d4🇩🇪20:d0:5e:66:fc:53:fe:1a:50:88:2c:78:db:28:52:ca:e4:74.

  2. 開啟 pyquickstart.py 並變更 path\to\cert 以指向您的新憑證。Open pyquickstart.py and change the path\to\cert to point to your new certificate.

  3. 儲存 pyquickstart.pySave pyquickstart.py.

執行 Python 應用程式Run the Python app

  1. 在 Git 終端機中使用 cd 命令以變更到 azure-cosmos-db-cassandra-python-getting-started 資料夾。Use the cd command in the git terminal to change into the azure-cosmos-db-cassandra-python-getting-started folder.

  2. 執行下列命令來安裝所需的模組:Run the following commands to install the required modules:

    python -m pip install cassandra-driver
    python -m pip install prettytable
    python -m pip install requests
    python -m pip install pyopenssl
    
  3. 執行下列命令來啟動節點應用程式:Run the following command to start your node application:

    python pyquickstart.py
    
  4. 從命令列確認結果符合預期。Verify the results as expected from the command line.

    按 CTRL + C 來停止執行程式,並關閉主控台視窗。Press CTRL + C to stop execution of the program and close the console window.

    檢視並確認輸出

  5. 在 Azure 入口網站中,開啟 [資料總管] 以查詢、修改及使用這個新資料。In the Azure portal, open Data Explorer to query, modify, and work with this new data.

    在資料總管中檢視資料

在 Azure 入口網站中檢閱 SLAReview SLAs in the Azure portal

Azure 入口網站會監視您的 Cosmos DB 帳戶輸送量、儲存體、可用性、延遲和一致性。The Azure portal monitors your Cosmos DB account throughput, storage, availability, latency, and consistency. Azure Cosmos DB 服務等級協定 (SLA) 相關聯的計量圖表會顯示相較於實際效能的 SLA 值。Charts for metrics associated with an Azure Cosmos DB Service Level Agreement (SLA) show the SLA value compared to actual performance. 此計量套件可讓您以更透明的方式監視監視 SLA。This suite of metrics makes monitoring your SLAs transparent.

若要檢閱計量和 SLA:To review metrics and SLAs:

  1. 在您的 Cosmos DB 帳戶導覽功能表中,選取 [計量] 。Select Metrics in your Cosmos DB account's navigation menu.

  2. 選取一個索引標籤 (例如 [延遲] ),並在右側選取時間範圍。Select a tab such as Latency, and select a timeframe on the right. 比較圖表中的實際SLA 的資料行。Compare the Actual and SLA lines on the charts.

    Azure Cosmos DB 計量套件

  3. 檢閱其他索引標籤中的計量。Review the metrics on the other tabs.

清除資源Clean up resources

完成您的 Web 應用程式和 Azure Cosmos DB 帳戶之後,您可以將建立的 Azure 資源刪除,以免產生更多費用。When you're done with your web app and Azure Cosmos DB account, you can delete the Azure resources you created so you don't incur more charges. 若要刪除資源:To delete the resources:

  1. 在 Azure 入口網站中,選取最左邊的 [資源群組] 。In the Azure portal, select Resource groups on the far left. 若已摺疊左側功能表,請選取展開按鈕加以展開。If the left menu is collapsed, select Expand button to expand it.

  2. 選取您在本快速入門中建立的資源群組。Select the resource group you created for this quickstart.

    Azure 入口網站中的計量

  3. 在新視窗中,選取 [刪除資源群組] 。In the new window, select Delete resource group.

    Azure 入口網站中的計量

  4. 在下個視窗中輸入要刪除的資源群組名稱,然後選取 [刪除] 。In the next window, enter the name of the resource group to delete, and then select Delete.

後續步驟Next steps

在本快速入門中,您已了解如何建立 Azure Cosmos DB 帳戶、如何使用 [資料總管] 建立容器,以及如何執行應用程式。In this quickstart, you've learned how to create an Azure Cosmos DB account, create a container using the Data Explorer, and run an app. 您現在可以將其他資料匯入到 Cosmos DB 帳戶。You can now import additional data to your Cosmos DB account.